The present invention relates to cooling fans. More particularly, the present invention relates to intelligent cooling fans for use in electronic systems and for designing cooling solutions for electronic systems.
In electronic systems, such as computer systems, cooling fans play an important role in maintaining their operational capabilities. The inability to remove excessive heat from electronic systems may lead to permanent damage of the system. Because of the complexity of existing electronic systems, cooling fans having added functionalities other than just providing cooling air, such as the ability to control the speed of a fan, the ability to monitor a tachometer pulse on a fan to determine instantaneous fan speed, and the ability to detect if a fan has failed or is slower than its preset speed, are required. Although these functionalities exist in some cooling fans today, there is no standard design or protocol that is available to control cooling fans produced by different manufacturers. Moreover, in order to implement these cooling fans within a system, specialized printed circuit assemblies (PCAs), also called controller cards, are required to be designed so as to provide signals that a fan can understand and also to receive and provide signals to the system in a form that is interpretable by the electronics of the system.
If one desires additional functionality, such as the ability for the fans to compensate for other failed fans by increasing speed, the ability for fans to notify external hardware that there is a problem, or the ability for fans to increase speed in response to increased system temperatures, a specialized PCA or controller card is also required. The PCA or controller card is designed and built to be capable of detecting a fan failure, notifying the system that a fan has failed, and adjusting the speeds of the other fans in the system. The design and manufacture of PCAs and controller cards involve a great deal of engineering time and resources, which ultimately add to the cost of the overall system utilizing the cooling fan(s).
Designing cooling solutions for new systems is also a time-consuming process for the thermal design engineer. Typically, the PCA or controller card is required to be designed and built for controlling the fan speed and other functionality, such as failure detection and alarm settings. Often times, the design and construction of multiple control cards are required so as to test them in real world applications to obtain the right combination of fans, fan speeds, alarm settings, etc. The multiple iterations of installing sample fans in a system, determining the adequate fan speeds and power required, and testing the fans in the system, for example, are costly and inefficient.
Another concern with conventional techniques for designing cooling fans is the ability to easily develop pulse trains for different motor and motor configurations. As explained above, existing techniques have been the use of custom ICs, which cannot be changed once designed.
Another concern involving conventional cooling fans, and in particular, direct current (DC) brushless cooling fans, is that they change speeds depending on the applied input voltage. As the input voltage is increased, the fans speed up and use more power. When input voltage is decreased, the fans decrease in speed and provide less cooling. Many typical applications have a voltage range that may vary between 24 to 74 volts. Accordingly, a system designer is charged with maintaining a constant cooling during these wide voltage swings. Accordingly, a voltage regulating power supply is usually installed in a system to keep the voltage to the fans constant. However, having to install a voltage regulating power supply adds additional complexity and cost to the overall system as well.